Method of treating leather and producing leather articles



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Patented Dec. 10, 1929 UNITED STATES PATENT OFFICE DAVID M. STRAUCHEN, OF ROCHESTER, NEW YORK, ASSIGNOR TO BITTER DENTAL MANUFACTURING 00., INC., OF ROCHESTER, NEW YORK, A CORPORATION OF DELA- WARE METHOD OF TREATING LEATHER AND PRODUCING LEATHER ARTICLES No Drawing.

The present invention relates to a method of treating leather and the productioirof articles therefrom, and also to a composition for treating leather and a new article or product resulting from the process employed. Une object of the invention is to providean improved process of treating or preparing leather selected from suitable stock to condition it for various usages, and more particularly to render it impervious to liquids or leak proof when subjected to different kinds of liquids such for example as Water, oils,

greases and other liquids or semi-liquid mati l) terials in connection with which the articles may be used in the different arts.

A further object of the invention is to provide an improved process of treating and forming leather or other pliable material of a fibrous nature to provide various shapes which may be required by different usages of the same, as in the case of packing to be used in various types of hydraulic machines.

A further object of the invention is to provide an improved process of treating tanned leather selected from suitable stock, which embodies first removing the impurities contained therein, and then impregnating it with certain materials in a liquid state capable of hardening and rendering it more or less impervious to various liquids and which at the same time will serve to strengthen and afi'ord a certain amount of rigidity to the leather whereby it will retain whatever shape it may be given, and whereby its wearing qualities and general serviceability will be increased.

A further object of the invention is to pro duce various articles of leather which will be impervious in liquids under relatively high or low degrees of pressure as for example packing to be used in different types of ydraulic machines.

A further object of the invention is to pro vide an improved composition for treating leather to improve its wearing qualities and to render it impervious to a number of different liquids.

To these and other ends the invention consists in certain improvements and combinations of parts, all as will be hereinafter more Application filed November 12, 1926. Serial No. 148,075.

fully described, the novel features being pointed out in the claims at the end of the specification.

Heretofore in producing packing from leather it has generally been stuffed or filled with fats and other foreign substances after for this purpose, since it is not impervious to liquids to the required degree and does not have the necessary mechanical strength in the service for which it is intended. Furthermore the stretching and mechanical working that ordinary leather is subjected to before marketing renders it unfit for forming into different shapes since it will not resist cracking under the pressures of different forming operations required in preparing it for servlce. v

In the present process the leather used is carefully selected, preferably from rough butt stock, just as tanned and before being treated, stretched or otherwise prepared for commercial purposes. In this state, due to lack of mechanical working, the arrangement of its fibers has not been interfered with and its natural strength is, therefore, retained. It is selected preferably from butt stock for the reason that this part of the hide is subjected to the least amount of stretching during the life of the animal and is free from grub holes and other natural defects. Leather of this character will have a minimum amount of impurities or natural inclusions but nevertheless will contain a certain percentage of gelatinous substances which are not removed y tanning, and which absorb considerable moisture from the atmosphere. These foreign substances mustbe removed and while water constitutes a good softening medium when preparing the leather for drawing or shaping it, it is obvious that it cannot be used where moisture is so objectionable and particularly since any albumens present in the leather would absorb and hold some of the water and increase rather than decrease the objectionable included matter. In preparing the selected leather stock described above for the reception of the difierent kinds of material to be applied thereto for the purpose of strengthening, hardening and rendering it mpervious to various liquids, it has been found that acetone is well suited for this purpose. It is not only satisfactory as a softening agent, but has the faculty of absorbing the moisture, albumens and other foreign substances present in the leather and of carrylng them off, leaving the pores of the leather open and perfectly free to absorb the filling materials to be applied thereto. These preferably constitute a composition applied in liquid form and embodying several different kinds of wax, each employed for a particular purpose, some of which may be omitted in accordance with certain variations in the charactertistics of the packing or leather in its final form, depending upon the degree of strength and hardness required in the diflerent uses to which it may be put as will appear hereinafter.

These materials include beeswax, carnauba wax, Montan wax. and a paraflin wax such as Parawax, each of which constitutes a different form of wax derived from different materials, and having somewhat different characteristics rendering them serviceable in their application to the present processes. Beeswaxis used as a base or filler while carnauba is used to harden and afford a slight shrinkage to the whole combination. Montan, which is a mineral wax is employed as a strengthening medium-andalso serves to slightly harden the compound whereby a certain amount of rigidity is afforded as in the case of carnauba wax. Parawax or parafiin is employed to afford penetration, due to its Beeswax 3 parts.- Carnauba n 1 part. Montan 1 part. Parafiin 1 parts.

In carrying out the present process, rough or uncurried leather of the class mentioned above is selected and cut to the desired shape and size, being skived to the proper thickness when required. Where the leather is to be used for packing it is out tothe shape of discs and provided with holes through the center of the correct diameters. The leather is then soaked in acetone or asuitable liquid capable of softening the same and of dissolving the gelatinous substances therein, being then removed and flexed by hand or otherwise as desired. The discs are then resoaked in acetone for a suitable period and are allowed to dry until bubbles no longer appear on the surface of the leather, thus indicating that the evaporation of the acetone and all included air, moisture, and impurities has been completed. As long as the evaporation of the acetone is going on there is little likelihood of moisture absorption taking place, but this will set in as soon as the fibers of the leather become thoroughly dry. Before evaporation of the acetone is completed or while the leather is in a relatively soft state the discs or other parts saturated with the acetone are placed in suitable moulds, shaping tools or dies and given the required shape. However, it is necessary to apply the wax or the wax composition as soon thereafter as possible following completion of the drying or evaporating period. At this time the leather is still very soft and pliable and should then have the wax applied thereto for the reason that in this state it is subjected to rapid absorption of moisture. However, before applying the wax, the packing may be turned to the desired thickness and to the proper angle on its inner face in a high speed lathe, using a suitable skiving tool, although this may be done before immersing it in the acetone if desired.

In preparing the several waxes for use they are preferably melted separately and then mixed, for the reason that some of them melt slowly at comparatively high temperatures, while others, such as Parawax have a relatively low melting point. The preshaped packings or other formed articles are then placed in the melted composition with the latter held at a suitable temperature, preferably'at about 185 Fahrenheit. They are retained in the melted wax at substantially this temperature for about fifteen minutes, after which the temperature is lowered to approximately 150 Fahrenheit, the packings being thereafter retained in the wax preferably for another period of about fifteen minutes after which time they are removed. As soon as possible after removing the sections from the melted composition, they are returned to the moulds or forming tools or to similar moulds and suitable pressure is then applied to maintain the required forms, time being allowed for drying or hardening of the wax in order that the parts may hold their shape when removed from the moulds.

In addition to the one and one-half parts of melted Parawax added to the liquid composition at the time of mixing the melted waxes additional Parawaxmay be added other articles prepared by the above described process, that all of the waxes mentioned above are preferably used but that when the leather in its final state is to be used for purposes where pliability or a relative degree of softness is required, one or more of the waxes which serve to harden,

. strengthen or afford rigidity to the leather may be omitted. Thus in some instances the beeswax and paraffin or Parawax may be used alone or together with either the carnauba or Montan wax, depending upon whether mechanical strength, hardness or slight shrinkage of the prepared leather is required, as afi'orded by the use of carnauba. The pressure to which the leather is to be subjected in use will also determine to a certain degree the strength and rigidity which must be imparted thereto, and hence the necessary materials required to be used in its preparation.

The improved composition mentioned above for treating leather, which is particularly adapted for treating leather packing, may include all of the waxes mentioned substantially in the proportions stated for the particular type of packing described. However, it need not necessarily include each wax mentioned, since the number and kinds of wax to be used, as stated above, will depend to a certain extent upon the nature and use of the finished article to be treated. In other words, where hardness and strength are not required to a marked degree, and where pliability of the leather is more essential, the hardening wax may be omitted. The same is true of the Montan or strengthening wax where a marked degree of strength is not required in the leather to be treated, as in cases where it will not be subjected to relatively high degrees of pressure in use. In cases where the leather is to be subjected to moderate degrees of pressure in use, or where hardness is required to a more or less limited degree the proportions of the composition stated above may be varied accordingly or as required.

Heretofore packings provided the usual manner for similar uses to that described have been found extremely inefiicient and a large percentage of them have failed under moderate pressure, the great majority being found to leak under a pressure of two or three hundred pounds per square inch. Packings constructed in accordance with the present method have been tested under considerably higher pressures than that mentioned above, and have been found to be absolutely impervious to oils and liquids with which they are used.

' While the present process is particularly useful in the production of an extremely high grade packing, it will be understood that it may be employed in the treating and forming of various articles of leather which are to be subjected to moisture or liquids from time to time where it is essential that they be so prepared as to resist penetration of the same.

I claim as my invention:

1. The method of treating leather of the class described which comprises imoregnating it with a suitable softening liquid, evaporating the liquid and subsequent to evaporation impregnating it with a melted Wax composition embodying beeswax, carnauba wax and a'paraffin wax.

2. The method of treating leather for the purpose describedwhich comprises impregnating it with acetone to soften the leather and to dissolve certain impurities contained therein, flexing the leather while impregnated with the acetone, allowing a period for evaporation of the acetone and at the end of said period impregnating it with a melted wax composition embodying beeswax, carnauba wax, Montan wax, and Parawax in substantially the proportions stated.

3. The method of producing an article of leather which comprises impregnating the leather With a liquid capable of softening the same, shaping it with suitable forming means while impregnated with said liquid, evaporating the liquid therefrom, subsequently impregnating the leather with a liquid composition capable of hardening the same and affording resistance to penetration by oils and other liquids and thereafter allowing the composition to harden While maintaining said shape.

4. The method of producing packing which comprises impregnating leather of the class described with acetone forthe purpose of softening the same and carrying off there-,

from the moisture and impurities contained therein, forming the leather to the desired shape While in a softened state, subsequently immersing the leather in a liquid composition embodying a plurality of different kinds of waxes and maintaining it in the liquid for a length of time sufficient to permit the leather to become thoroughly impregnated with the wax and allowing the wax therein to harden while maintaining said shape.

DAVID M. STRAUCHEN. 

